The invention relates to building panels which can be assembled, on site, to produce a self-supporting building assembly adaptable to many uses.
Pre-fabricated buildings, or "knock-down buildings" have been developed for many years and have many applications such as living quarters for people or animals, storage of equipment, temporary workshops, etc. A wide variety of building materials has been used, and the present invention is particularly adapted to the type of composite material commonly known as fibre reinforced cement. In the past, asbestos fibres were used, but nowadays safer alternative fibres are available, some being of wood products. This reinforced material is characterized by relatively low cost, high fire resistance, high thermal insulation, low maintenance requirements particularly with reference to rot and mildew problems, and the ability to be fabricated using "low technology" methods and equipment, which is particularly applicable for use in third world countries.
However, one problem associated with fibre reinforced cement building panels is that they tend to be relatively heavy in order to provide sufficient strength to overcome inherent weakness of the material when subjected to tensile stresses. Failure under low tensile stresses can occur when a poorly supported panel sags or bends under its own weight. Steel reinforcing may be needed in some prior art panels.
Prior art buildings assembled from fibre reinforced cement building panels usually require additional support members to provide adequate strength both to sustain the weight of the relatively heavy building panels, and to support the panels against deformation under their own weight. Such buildings commonly require specialized equipment for erection, and thus weight of the panels limits their use to areas having adequate transportation services for delivering the heavy panels to the building site.
Some prior art buildings are made from sheet metal, particularly rust resistant steel. A building panel particularly adapted for fabrication from sheet metal is disclosed in Canadian Pat. No. 1,004,822 and U.S. Pat. No. 3,874,141. The panels of the above patents derive their strength from the three-dimensional configuration of the plates, which are generally a ribbed and folded symmetrical quadrilateral with means for connecting to adjacent similar panels along edges of the panels. The panels of this patent can be fabricated relatively easily from sheet steel, and are lightweight and thus can be easily erected by relatively unskilled labour at the building site. However, the cost of sheet steel can be prohibitive in some third world countries, and thus buildings assembled from steel panels of this type are not economical for use in such situations.